Several Polycarbonate diols comprising alkylene diols units are disclosed in the state of the art. In particular, patent document EP1288241 discloses polycarbonate diol comprising 1,6-hexanediol units and 1,5-pentanediol or 1,4-butanediol units, EP2213696 discloses polycarbonate diol comprising 1,6-hexanediol units and 1,4-butanediol units, EP2213695 discloses polycarbonate diol comprising 1,6-hexanediol units and 1,5-pentanediol units. These patent documents disclose that these polycarbonate diols have low crystallinity.
Moreover, polycarbonate diols (PCD) disclosed in the above-mentioned patent documents do not have reactive functional group other than hydroxyl groups. Therefore, these PCD were not suitable in order to produce polyurethane with higher crosslink density.
On the other hand, the patent application DE 1568342 discloses linear polyesters containing carbonate groups with predominantly hydroxyl terminations of the general formula
in which “n” stands for integers from 1 to 20, preferably 1 to 15, “m” for integers from 1 to 10, “Q” for the 1,4-dimethylene-cyclohexane radical and “R” for a saturated or unsaturated aliphatic or cycloaliphatic alkene radical or an arylene radical (except for the 1,4-phenylene radical). Products disclosed in that patent application show a high elasticity, even without the addition of softeners. Their adhesiveness is very good on automotive sheet metal and satisfactory on glass. In addition, these products are very soluble in the usual lacquer solvents, such as acetone, methyl ethyl ketone and acetic acid ethyl ester. Their adhesive capacity is excellent. However, the linear polyesters disclosed in patent application DE 1568342 are characterized by a high viscosity (see the comparative example).